This invention relates to nozzles for gas turbine combustion systems and more specifically relates to a novel atomizing air metering nozzle using an aerodynamically rotating orifice having improved erosion resistance performance in dual fuel and oil-only air atomized fuel nozzles.
Nozzles are well known for atomizing liquid fuels with air for efficient combustion for use in connection with gas turbine systems. In one known nozzle arrangement, a fuel such as oil is sprayed through an interior opening and is atomized by an air flow which intercepts the oil supply. Natural gas or a low BTU fuel, such as coal-derived gases, may also be used in these dual fuel nozzles, such as disclosed in copending application Ser. No. 018,932 filed Mar. 3, 1979 in the names of Robert A. Battista and William A. Hibbins and entitled "Low BTU Fuel Nozzle."
It has been found that there is excessive erosion on the atomizing air side of such nozzles. This erosion is caused by the entrapment of airborne particles in a highly rotating atomizing air path around the inside wall of the outer fuel nozzle tip. This causes erosion through the outer fuel nozzle tip outer wall to the gas side of the nozzle.
The rate of erosion in these prior art nozzles is significantly increased when using a higher atomizing air pressure ratio which increases the spinning and centrifugal forces on heavier particles. This erosion problem makes frequent inspection and replacement of parts necessary in order to prevent possible hazardous conditions.